Project Summary/Abstract The current state of basic elder mistreatment (EM) science on risk factors and consequences to inform the development of effective primary, secondary, and tertiary prevention interventions is constrained by a literature with substantial methodological limitations. In particular, the field lacks longitudinal population-based research inclusive of vulnerable older adult sub-populations that provides generalizable and causally-inferred information. Further, population-based research to date has limited EM measurement to binary (no/yes) outcomes that obscure the variation in severity characterizing this issue. The goal of the proposed project is to overcome long-standing methodological limitations in the EM literature to advance more generalizable basic science on EM risk factors and consequences and to integrate severity into understanding of the problem. This study will collect a second wave of data (nine years post) from the population-based New York State Elder Mistreatment Prevalence Study (NYSEMPS). Drawing on a representative, probability Wave 1 sample, direct telephone interviews will be conducted with a follow-up sample (n = approx.1555) of older adults or close proxies, regardless of cognitive status or living setting to address the following aims: 1) identify longitudinal EM risk factors for older adults in the general population, 2) describe how EM severity changes over time among victims and identify factors predicting changes in severity, 3) identify longitudinal EM health consequences, and 4) understand the relationship between EM severity and adverse health consequences. The proposed study adheres to accepted conceptual boundaries that define EM as a distinct form of victimization and is informed by a longitudinal stress process conceptual framework. The methodological advancements underlying the proposed study have the capacity to generate the most valid, reliable, and generalizable information on EM risk factors, consequences, and severity to date. Findings from this study will directly inform targeted primary, secondary, and tertiary EM prevention interventions.